Maintenance of high-power electric cables comes of age
High-tension electric lines cover thousands of kilometres across Europe, often passing through remote and inaccessible areas. This makes inspecting them for issues such as corrosion and overheating difficult and even dangerous, prompting a need for a more advanced solution that is less labour intensive. The EU-funded project CHAPLIN (High power transmission line cable inspection) developed efficient, cost-effective inspection technology that uses ultrasonic guided wave testing to locate defects in phase and ground wire conductor cables. It envisioned equipment for continuous monitoring that can be lowered on the cables by helicopter or robot, extending rapid testing capabilities to energy providers and authorities. To achieve its aims, the project articulated system specifications and industrial requirements, including detailed specifications for device modelling, prototype development and testing, as well as required transducers, electronics and software. It reviewed the world cable standard, researching typical defects and their causes, in addition to articulating testing requirements. The project evaluated the use of ultrasonic guided waves in cables to pinpoint defects and examined how the waves propagate along the cable. It then designed the relevant transducers and arrays for the ultrasonic tests. This was followed by sensor and laboratory trials, resulting in the selection of shear wave transducers for the project. Development progress with respect to wireless data communication and signal processing resulted in a working wireless data communication protocol as well as the relevant software required. By the end of the project the team had built a fully integrated working hardware and software system that was fitted on to the cable, performing much better than expected. The motorised inspection prototype tool was also tested on cables in the lab and in real conditions, setting the stage for a radically new solution in the field. This has the potential to reduce inspection costs significantly and address blackouts or downtime much more quickly, even when compared to the latest inspection techniques on the market. Less maintenance will also mean an important fall in operational costs. In other words, the project's work paves the way for a revolutionary system that will make European electric grids more dependable and less expensive to maintain and operate.
Keywords
High-power electric cables, transmission line, cable inspection, ultrasonic guided wave